Suede-like man made leathers having long naps, nubuck-like man made leathers having short naps, full grain type man made leathers having no nap, grain type nubuck-like man made leathers partially having short naps and the like are cited as main types of man made leathers in these years. These man made leathers are formed mainly by using nonwoven fabrics, and various proposals have been made for making these man made leathers bearing a resemblance in appearance as closely as possible to high quality natural leathers.
For example, in nubuck-like man made leathers, Japanese Patent Publication No. 62-42076 describes a process for producing a sheet-shaped material having naps consisting of ultrafine fibers wherein the base material is impregnated or coated with a resin to immobilize the naps, subsequently the napped surface is pressed by a calender roll to make the naps lie closely on the surface, and then the surface is buffed to raise naps. Japanese Patent Publication No. 62-42075 describes a process for producing a sheet-shaped material having naps consisting of ultrafine fibers wherein the napped surface is pressed by a calender roll to make the naps lie closely on the surface, and subsequently, the base material is impregnated or coated with a resin, and then the surface is buffed to raise naps. Japanese Patent Publication No. 6-33577 describes a process wherein an elastomeric polymer is applied on a fibrous sheet which comprises an ultrafine fiber-entangled nonwoven fabric having a single fineness of no greater than 0.3 de and containing the elastomeric polymer in it, the sheet is optionally embossed and buffed, and subsequently the sheet is subjected to an area contraction of 10% or more so that napped parts and grained parts are mixed in the surface. Japanese Unexamined Patent Publication No. 3-161576 describes a process for producing a nonwoven fabric comprising fibers convertible into ultrafine fibers wherein the fibers only in the surface layer are made ultrafine at first, then the nonwoven fabric is impregnated with an elastomeric resin, the resin is coagulated, subsequently the nonwoven fabric is treated under conditions that the fibers in the inner part of the nonwoven fabric are extracted with a solvent or the like to make them ultrafine, and then the outermost surface is napped. Further, Japanese Unexamined Patent Publication No. 4-136280 describes a process wherein a liquid of a composition containing non-fibrous collagen powder having an average particle diameter of no greater than 10 .mu.m and an apparent density of 0.1-0.3 g/cm.sup.3, and a polymer composed mainly of polyurethane is applied on the surface of a fibrous sheet comprising a fiber assembly containing a polymer composed mainly of an elastomeric polymer; the fiber sheet is subjected to an emboss processing; and subsequently the embossed coated surface is treated for raising naps. Further, Japanese Unexamined Patent Publication No. 7-133592 describes a process wherein on the surface of a fibrous base layer having smooth surface which comprises entangled nonwoven fabric comprising ultrafine fibers and/or ultrafine-fiber bundles and dense foamed bodies of an elastomeric polymer existing in entanglement spaces, is formed ultrafine naps which continue to ultrafine fibers that constitute the fibrous base layer; subsequently a resin composed mainly of an elastomeric polymer is applied on the napped surface to form a porous layer which is integrated with the naps; and further this is subjected to a napping treatment to make a part of the ultrafine naps be exposed on the surface of the sheet.
Nubuck-like man made leathers produced according to the conventional processes have short naps, and their surfaces are smooth; however, the quantities of fibers on the surfaces are extremely smaller than those of natural leathers, and larger parts of the surface are occupied not by napped parts consisting of ultrafine fibers but by resin parts consisting of elastomeric polymer and space parts. Thus, a nubuck-like man made leather having sharp writing effect attributable to extremely high nap density as in natural leathers, and exhibiting sticking soft-and-smooth touch while giving a dry feeling has not been proposed yet.
As for full grain type man made leathers, Japanese Patent Publication No. 4-8547 describes a process for producing a porous sheet material by wet coagulation of a polymer solution composed mainly of a polyurethane elastomer with a coagulant solution wherein to the coagulant solution is added an ethylene oxide adduct of at least one compound selected from higher alkyl amines, higher alcohols, sorbitan fatty acid esters and others; and a polymer solution free from the ethylene oxide adduct is coagulated by using the resulting coagulant solution. The full grain type man made leather which is produced by this process is excellent in smoothness of the surface; however, spaces between wrinkles formed on the man made leather when it is bent are larger than spaces between fine wrinkles formed on a natural leather, and the man made leather has high repulsion attributable to its homogeneous sponge-structure and exhibits a rubber-like feeling. Further, Japanese Unexamined Patent Publication No. 4-185777 describes a full grain type man made leather that is composed of a base layer comprising a nonwoven fabric which comprises ultrafine-fiber bundles and microporous urethane binder, and has a weight ratio of the ultrafine fiber bundles to the polyurethane of 70/30 to 97/3 and an apparent density of 0.5-0.8 g/cm.sup.3, and a resin-made nonporous layer having a modulus of 20-150 kg/cm.sup.2 at 100% elongation and a thickness of 10-100 .mu.m. A full grain type man made leather produced by this process has a low repulsion and a good fine wrinkle feeling on bending, but its flexibility is not sufficient in spite of the application of a softening processing on it because the man made leather is constituted with a nonwoven fabric having such a high apparent density as 0.45 g/cm.sup.3 or more. Thus, in full grain type man made leathers produced according to the conventional processes, man made leathers which are satisfactory in all of the properties that are characteristics to natural leathers, such as soft feeling, low repulsion, extremely smooth surface and very delicate fine wrinkle feeling on bending have not been achieved yet.
The object of the present invention, therefore, is to provide man made leathers having dense, delicate, high quality appearance, which are not obtained in conventional man made leathers, and bearing a resemblance to high quality natural leathers: for example, nubuck-like man made leathers having high class image of nubuck appearance characteristic of natural leathers, i.e. having sharp writing effect and exhibiting sticking soft-and-smooth touch while giving a dry feeling; grain type nubuck-like man made leathers having unique surface feeling; and full grain type man made leathers excellent in flexibility and surface smoothness, and exhibiting a delicate fine wrinkle feeling.